1. Field of the Invention
The present invention relates to acoustic devices, and more particularly to a phased beam transducer device for acoustic beam steering.
2. Background Art
Conventional planar sound receiver and/or transmitter devices for sonar systems use mechanically tilted transducers or electrically phased arrays to produce a steered acoustic beam. Mechanically tilting a transducer is an effective method to achieve a steered beam, but it is not practical for many underwater applications. When mounted on the hull of a ship or underwater vehicle, where the surface must be hydrodynamic, the amount the transducer can be mechanically tilted can be severely limited.
Alternatively, an array of transducers can be mounted flush with the vehicle surface and produce beams steered as far as 60.degree., but a different phase shift or time delay circuit is required for each element. The more the beam is steered, the closer together the elements need to be. Typically, elements are spaced a half-wavelength apart and the array is many wavelengths in dimension. Two dimensional arrays typically have the same number of elements in both planes: i.e., an eight element line array turns into a sixty-four element planar array. To form a single steered beam each element requires a phase shifter.